如何在Xamarin Android（Widget）中动态更改ImageView源

Question

我创建了Android窗口小部件，所以我想动态更改图像源。我尝试过的小部件代码无法加载，但是当我删除更改ImageView源的代码时，它加载正常。

这是我的代码。

   int test = (int)typeof(Resource.Drawable).GetField("Cloud").GetValue(null);



    public override void OnUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
    {

        var x = new ComponentName(context, Java.Lang.Class.FromType(typeof(AppWidget)).Name);

        appWidgetManager.UpdateAppWidget(x, BuildRemoteViews(context, appWidgetIds));


    }

    private RemoteViews BuildRemoteViews(Context context, int[] appWidgetIds)
    {

        var widgetView = new RemoteViews(context.PackageName, Resource.Layout.widget);


        LoadData(widgetView);


        return widgetView;
    }

    private void LoadData(RemoteViews widgetView)
    {

        widgetView.SetTextViewText(Resource.Id.widgetCity,city);
        widgetView.SetTextViewText(Resource.Id.widgetWeatherDescription, description);
         widgetView.SetImageViewResource(Resource.Id.widgetIcon, test); //This line fails the widget from loading          

    }

我可能做错了什么，或者我可以采取什么措施解决此问题。我正在使用Xamarin Android

Answer 1

由于您的代码不完整，所以我写了一个简单的示例，您可以检查它。

我将一个点击事件添加到ImageView，当您单击imageview时，它将更改图像资源。

[BroadcastReceiver(Label = "HellApp Widget")]
[IntentFilter(new string[] { "android.appwidget.action.APPWIDGET_UPDATE" })]
// The "Resource" file has to be all in lower caps
[MetaData("android.appwidget.provider", Resource = "@xml/appwidgetprovider")]
public class AppWidget : AppWidgetProvider
{
    private static string AnnouncementClick = "AnnouncementClickTag";
    private int test = (int)typeof(Resource.Drawable).GetField("fivePlus").GetValue(null);
    /// <summary>
    /// This method is called when the 'updatePeriodMillis' from the AppwidgetProvider passes,
    /// or the user manually refreshes/resizes.
    /// </summary>
    public override void OnUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
    {
        var me = new ComponentName(context, Java.Lang.Class.FromType(typeof(AppWidget)).Name);
        appWidgetManager.UpdateAppWidget(me, BuildRemoteViews(context, appWidgetIds));
    }

    private RemoteViews BuildRemoteViews(Context context, int[] appWidgetIds)
    {
        // Retrieve the widget layout. This is a RemoteViews, so we can't use 'FindViewById'
        var widgetView = new RemoteViews(context.PackageName, Resource.Layout.Widget);

        LoadData(widgetView);
        RegisterClicks(context, appWidgetIds, widgetView);
        return widgetView;
    }


    private void LoadData(RemoteViews widgetView)
    {

        widgetView.SetTextViewText(Resource.Id.widgetMedium, "HelloAppWidget");
        widgetView.SetTextViewText(Resource.Id.widgetSmall, string.Format("Last update: {0:H:mm:ss}", DateTime.Now));

    }

    private void RegisterClicks(Context context, int[] appWidgetIds, RemoteViews widgetView)
    {
        var intent = new Intent(context, typeof(AppWidget));
        intent.SetAction(AppWidgetManager.ActionAppwidgetUpdate);
        intent.PutExtra(AppWidgetManager.ExtraAppwidgetIds, appWidgetIds);

        // Register click event for the Background
        var piBackground = PendingIntent.GetBroadcast(context, 0, intent, PendingIntentFlags.UpdateCurrent);
        widgetView.SetOnClickPendingIntent(Resource.Id.widgetBackground, piBackground);

        // Register click event for the Announcement-icon
        widgetView.SetOnClickPendingIntent(Resource.Id.widgetAnnouncementIcon, GetPendingSelfIntent(context, AnnouncementClick));
    }

    private PendingIntent GetPendingSelfIntent(Context context, string action)
    {
        var intent = new Intent(context, typeof(AppWidget));
        intent.SetAction(action);
        return PendingIntent.GetBroadcast(context, 0, intent, 0);
    }

    /// <summary>
    /// This method is called when clicks are registered.
    /// </summary>
    public override void OnReceive(Context context, Intent intent)
    {
        base.OnReceive(context, intent);

        // Check if the click is from the "Announcement" button
        if (AnnouncementClick.Equals(intent.Action))
        {
            try
            {
                RemoteViews remoteViews = new RemoteViews(context.PackageName, Resource.Layout.Widget);
                remoteViews.SetImageViewResource(Resource.Id.widgetAnnouncementIcon, Resource.Drawable.fivePlus);
                AppWidgetManager appWidgetManager = AppWidgetManager.GetInstance(context);
                ComponentName componentName = new ComponentName(context, Java.Lang.Class.FromType(typeof(AppWidget)).Name);
                appWidgetManager.UpdateAppWidget(componentName, remoteViews);
        }
            catch
            {
                // Something went wrong :)
            }
        }
    }
}